By the way what was your logic while calculating 6121? The same as of mine??

Click to expand...

Heh, no, I did it in a spreadsheet and made a BIG assumption...column A contained the original sequence in A1-A5; B2=A2-A1 and copied the formula to B3-B5, C3-C5, D4-D5 and E5. I assumed that was the end of it and that the next row, if it existed, would end with E6=E5 and worked backwards to find out what would be in D6, C6, B6 and A6, and that's where I got 6121 from.

Then I looked up the sequence in the sequences database as explained (and linked) earlier in the thread.